J/ApJ/885/131 ∼200 high-mass SFR plx & proper motion with VLBI (Reid+, 2019)
Trigonometric parallaxes of high-mass star-forming regions: our view of the
Milky Way.
Reid M.J., Menten K.M., Brunthaler A., Zheng X.W., Dame T.M., Xu Y., Li J.,
Sakai N., Wu Y., Immer K., Zhang B., Sanna A., Moscadelli L., Rygl K.L.J.,
Bartkiewicz A., Hu B., Quiroga-nunez L.H., Van Langevelde H.J.
<Astrophys. J., 885, 131-131 (2019)>
=2019ApJ...885..131R 2019ApJ...885..131R (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way; Star Forming Region; Parallaxes, trigonometric;
Proper motions; Interferometry
Keywords: Milky Way; Milky Way dynamics; Milky Way rotation
Trigonometric parallax; Star formation; Gravitational wave sources
Abstract:
We compile and analyze approximately 200 trigonometric parallaxes and
proper motions of molecular masers associated with very young
high-mass stars. Most of the measurements come from the BeSSeL Survey
using the VLBA and the Japanese VERA project. These measurements
strongly suggest that the Milky Way is a four-arm spiral, with some
extra arm segments and spurs. Fitting log-periodic spirals to the
locations of the masers, allowing for "kinks" in the spirals and using
well-established arm tangencies in the fourth Galactic quadrant,
allows us to significantly expand our view of the structure of the
Milky Way. We present an updated model for its spiral structure and
incorporate it into our previously published parallax-based
distance-estimation program for sources associated with spiral arms.
Modeling the three-dimensional space motions yields estimates of the
distance to the Galactic center, R0=8.15±0.15kpc, the circular
rotation speed at the Sun's position, Θ0=236±7km/s, and
the nature of the rotation curve. Our data strongly constrain the full
circular velocity of the Sun, Θ0+V☉=247±4km/s, and
its angular velocity,
(Θ0+V☉)/R0=30.32±0.27km/s/kpc. Transforming the
measured space motions to a Galactocentric frame which rotates with
the Galaxy, we find non-circular velocity components typically
≲10km/s. However, near the Galactic bar and in a portion of the
Perseus arm we find significantly larger non-circular motions. Young
high-mass stars within 7kpc of the Galactic center have a scale height
of only 19pc, and thus are well suited to define the Galactic plane.
We find that the orientation of the plane is consistent with the
IAU-defined plane to within ±0.1°, and that the Sun is offset
toward the north Galactic pole by Z☉=5.5±5.8pc. Accounting
for this offset places the central supermassive black hole, Sgr A*, in
the midplane of the Galaxy. The measured motions perpendicular to the
plane of the Galaxy limit precession of the plane to ≲4km/s at the
radius of the Sun. Using our improved Galactic parameters, we predict
the Hulse-Taylor binary pulsar to be at a distance of
6.54±0.24kpc, assuming its orbital decay from gravitational
radiation follows general relativity.
Description:
Very Long Baseline Interferometry (VLBI) arrays have been used to
measure parallaxes and proper motions for about 200 maser sources
associated with young massive stars. They include results from the
National Radio Astronomy Observatory's Very Long Baseline Array
(VLBA), the Japanese VLBI Exploration of Radio Astrometry (VERA)
project, the European VLBI Network, and the Australian Long Baseline
Array.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 129 199 Parallaxes & proper motions of high-mass star
forming regions
refs.dat 93 78 References used
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See also:
V/112 : Catalog of Star-Forming Regions in the Galaxy (Avedisova, 2002)
J/ApJ/720/1055 : VBLA observations of W51 Main/South (Sato+, 2010)
J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)
J/ApJ/834/142 : Gould's Belt Distances Survey (GOBELINS). II. (Kounkel+, 2017)
J/ApJ/864/136 : Massive star-forming regions multiwave. study (Binder+, 2018)
J/ApJ/874/16 : SOFIA Massive Star Formation Survey. II. (Liu+, 2019)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Source name
16- 30 A15 --- OName Other name
32- 33 I2 h RAh [0/24] Hour of Right Ascension (J2000)
35- 36 I2 min RAm Minute of Right Ascension (J2000)
38- 44 F7.4 s RAs Second of Right Ascension (J2000)
47 A1 --- DE- [±] Sign of the Declination (J2000)
48- 49 I2 deg DEd Degree of Declination (J2000)
51- 52 I2 arcmin DEm Arcminute of Declination (J2000)
54- 59 F6.3 arcsec DEs Arcsecond of Declination (J2000)
63- 67 F5.3 mas plx [0.04/2.43] Trigonometric Parallax (1)
69- 73 F5.3 mas e_plx [0.005/0.2] Uncertainty in plx
77- 82 F6.2 mas/yr pmE [-6.9/3.13] Eastward Proper Motion (2)
84- 87 F4.2 mas/yr e_pmE [0.06/3.1] Uncertainty in pmE
91- 96 F6.2 mas/yr pmN [-9.36/2.67] Northward Proper Motion (3)
98-101 F4.2 mas/yr e_pmN [0.1/3.8] Uncertainty in pmN
105-108 I4 km/s VLSR [-76/121] Local Standard of Rest velocity (3)
110-111 I2 km/s e_VLSR [3/40] Uncertainty in VLSR
114-116 A3 --- Arm Spiral arm designator (4)
119-129 A11 --- Ref Reference designators
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Note (1): Parallax uncertainties for sources with multiple (N) maser spots
have been adjusted upwards by sqrt(N), if not done so in the
original publications.
Note (2): Motion in RA multiplied by cos(Dec)
Note (3): Some parameter values listed here are preliminary ones and may be
slightly different from final values appearing in published papers.
Motion components and their uncertainties are meant to reflect that
of the central star that excites the masers, and may be larger than
formal measurement uncertainties quoted in some papers.
Note (4): Designators as follows:
GC = Galactic Center region (3 occurrences)
Con = Connecting arm (1 occurrence)
3kN = 3-kpc arms near (5 occurrences)
3kF = 3-kpc arms far (1 occurrence)
Nor = Norma arm (12 occurrences)
Out = Outer arm (11 occurrences)
ScF = Scutum arm far (12 occurrences)
ScN = Scutum arm near (30 occurrences)
CtN = Centaurus arm near (4 occurrences)
OSC = Outer Scutum Centaurus arm (1 occurrence)
SgN = Sagittarius arm near (19 occurrences)
SgF = Sagittarius arm far (19 occurrences)
CrN = Carina arm near (1 occurrence)
Loc = Local arm (28 occurrences)
Per = Perseus arm (41 occurrences)
LoS = Local arm spur (5 occurrences)
AqS = Aquarius spur (3 occurrences)
??? = Unassigned (3 occurrences)
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref [1/78] Reference number
4- 32 A29 --- Autor Main autor
34- 52 A19 --- BIB BIBcode
54- 67 A14 --- Cat Catalog reference
69- 93 A25 --- Note Note or comment
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 16-Sep-2021